Install all of the necessary packages referenced in the Gruntfile: npm install grunt-contrib-uglify grunt-contrib-qunit grunt-contrib-concat grunt-contrib-watch --save-dev. --save-dev will also modify package.json with the new dependencies (under devDependencies).

DEPRECATION: Action handlers implemented directly on controllers are deprecated in favor of action handlers on an actions object

Can also mean that an error has been thrown and your ApplicationController does not define an 'error' action (or EmberJS has created you an 'error' action and its incorrectly misinterpreting it as a directly implemented action? I have no idea).

This looks like an EmberJS bug and I guess it can be ignored - any other errors will be correctly reported (just sadly with no reliable stacktrace).

arrangedContent.addArrayObserver is not a function

Are you trying to #each over a bare JS object rather than an Ember array? e.g. instead of going:

Hooking to valueBinding

Prevent JQuery.ajax.error from triggering an error state in Ember

Normally if you call $.ajax() and the requests results in an error, your errorCallback will still be called, but then Ember in all its wisdom will redirect you to the error state regardless.

One way to solve this is to wrap the AJAX call in a Promise, which prevents the error state from being called - it looks like Ember assumes that a JQuery.ajax() error can reject the entire Promise within say, an afterModel callback.

TypeError: cyclic object value

Make sure that you aren't trying to save an object property that isn't a DS.Model object. If you are, you may need to define a transient flag on the property, so that the JSONSerializer does not try to serialize the cycle: see Transient DS.Model Attributes in EmberJS.